Add CI integration

[zugaldia]

Once #1 gets merged, we need to add this project to Bitrise.

cc: @Guardiola31337 @tobrun

[tobrun]

Basic bitrise integration landed and is now active for every push to this repo.

To close this we need:

• versioned bitrise.yml setup
• checkstyle
• unit testing
• roboto tests on firebase
• slack integration